Conventional PBX telephone systems are being replaced with voice over IP telephones that use the Internet instead of the public switched telephone network. When the user of one IP telephone wishes to dial the user of another IP telephone in the same telephone system, the calling party's telephone communicates with a call manager and identifies the extension or other number of the called party. Although two parties are specified as being on the phone call for purposes of example, calls may be multiparty calls. The call manager identifies the IP address of the called party's telephone and communicates the IP address to the calling party's telephone. The telephones then establish an IP session and transfer the digitized voice and any control signals between themselves.
When the call is disconnected, each of the two telephones provide to the call manager a call detail record describing the called and calling party's IP addresses, the date and time the call was started and ended, the number of packets sent and received, and certain potential problem reports, such as the number of packets that were lost, the jitter, which is a measure of the variation of time it took packets to be received, and latency, the amount of time between when the packet was sent and when it was received.
The call detail records from several calls can be summarized by the call manager and presented in report form to a system administrator to allow the system administrator to identify the quality of service being provided. If a large percentage of packets are dropped, for example, the quality of service can be quite poor, making calls that use a voice over IP telephone system inferior to calls made over a PBX system.
Unfortunately, although the reports the system administrator receives can indicate a problem with the network being used to transport the calls, the system administrator is not provided with information that is useful in fixing the problem. For example, if the source of the dropped packets is a node in the path between the two telephones that intermittently fails, the system administrator, armed only with the reports from the call manager, will have no idea how to fix the underlying source of the lost packets. Because voice over IP telephones can be much more sensitive to network problems than data traffic, conventional network monitoring tools that may be in use may not identify the network problems that are causing the problems with the voice over IP traffic.
What is needed is a system and method that can help pinpoint problems with a network that can be causing problems for voice over IP telephones.